This invention relates to electrical interface arrangements which are suitable for use with apparatus for testing circuits formed as flat boards. It is becoming increasingly common to form electrical circuits, as what are generally termed printed circuit boards, which comprise an insulating lamina with conductive tracks formed on one or both of its outer surfaces. The circuit components, such as resistors, capacitors, transistors, etc., which are electrically interconnected by means of these conductive tracks are generally mounted on only one side of the insulating lamina. Circuit boards of this kind can be very complex indeed and special techniques are needed to thoroughly test them after manufacture to ensure that the interconnections have been correctly made, that the components are not defective, and that the circuit operates correctly in the intended manner.
One of the problems which arises in testing a printed circuit board is that of making electrical connection to predetermined locations of it in a reliable and consistent manner, and it is usually necessary to employ a special electrical interface between the test equipment and the circuit under test. The electrical interface includes a two dimensional array of contact points positioned in a predetermined pattern so that they touch specified locations of the conductive tracks carried by the circuit board. In order that contact is made exactly at the specified locations, the circuit board must be accurately aligned with the array of contacts and held firmly against them. Because circuit boards can be fairly large and the insulating lamina can be fairly thin, they are flexible to a certain extent and, to ensure proper electrical contact, the board must be firmly supported across its surface area.
Various methods of support are available which are suitable for different kinds of circuit boards, and some methods are more suitable than others depending on the nature of the circuit and the kind of access to it which might be needed whilst it is actually being tested. It has been customary to provide an electrical interface arrangement which is capable of providing support in only one predetermined manner and this results in duplication of expensive equipment and can significantly increase manufacturing costs.
The present invention seeks to provide a more versatile electrical interface arrangement in which these difficulties are reduced.